Switch actuating device



Sept. 29, 1970 q THOMPSON ETI'AL 3,531,606

SWITCH ACTUATING DEVICE Filed March 22, 1968 2 Sheets-Sheet 1 INVENTORS. ''istsc Z. aape r d'esfer A. flan v10),

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Sept. 29, 1970 c, THOMPSON ETAL 3,531,606

SWITCH ACTUATING DEVICE Filed March 22, 1968 2 Sheets-Sheet 2 United States Patent O US. Cl. ZOO-81.9 8 Claims ABSTRACT OF THE DISCLOSURE Switching apparatus for actuating a switch in response to air flow. An elongated ribbon or strip is connected to a grill-shaped bracket adapted to extend across a fluid duct. The strip is connected to a switch arm and a predetermined air flow causes the strip to be blown from a position in which the switch arm is in one mode to a position in which the switch arm is moved to another mode.

BACKGROUND OF THE INVENTION This invention relates to a switch actuating device and more particularly to a device adapted to sense air movement and then actuate a switch.

Devices for sensing air flow and actuating switches in response to such air flow are well known. These switches, and the actuating devices therefor are sometimes referred to as sail switch devices. They are utilized in many types of apparatus environments wherein it is desired to control the operation of a piece of equipment in response to the existence or nonexistence of air flow. For example, sail switches have been utilized in heating and air conditioning ducts to operate various components in response to air flow in the ducts.

One of the difliculties of many of such devices is that the sail or actuating portion which is influenced by the air flow must be mounted in a vertical plane. This is because the sail apparatus, if mounted in a horizontal plane, is influenced by gravity which naturally either adds or subtracts from the air force necessary to move the sail apparatus to an actuating position. In many instances the gravitational effect would render impossible the utilization of the sail in a horizontal plane.

Furthermore, many of the sails had to be relatively large to cause actuation of a switch. The largeness of such sails naturally affected the air flow characteristics of the duct in which the sail was located. The present invention obviates many of the disadvantages of prior known sail switches.

SUMMARY OF THE INVENTION Briefly, this invention relates to switching apparatus comprising a support, a switch mounted on the support and having a switch arm movable between a switch actuating position and a switch de-actuating position, the support having an elongated portion extending away from the switch, an elongated sail strip connected at one end to the switch arm and connected at the other end to the elongated portion at a point spaced from the switch arm, the sail strip, in the absence of fluid flow thereagainst, being held in one predetermined position relative to the elongated portion by the switch arm and to the support, the switch arm, in the absence of fluid flow against the strip being in one of its said positions, the sail strip, in response to the flow of fluid thereagainst, moving from the one predetermined position and moving the switch arm from its position, the sail strip, when moved a predetermined amount from the one predetermined position, moving the switch arm to the other of its positions.

One of the primary objects of this invention is to provide a switch device responsive to air flow for actuation, which device is adapted to operate effectively Without regard to the plane in which it is located.

Another object of this invention is to provide a switch device of the type described which does not provide a substantial restriction to air flow.

A further object of this invention is to provide a switch device such as described which is economical in construction and efiective in operation.

Other objects and advantages of this invention will be made apparent as the description progresses.

BRIEF DESCRIPTION OF THE DRAWINGS Referring now to the drawings in which one of several various embodiments of this invention is shown,

FIG. 1 is a side elevation of a furnace having an electronic air cleaner equipped with a switch device of this invention;

FIG. 2 is a perspective view of an electronic air cleaner with the switch device of this invention shown therewith;

FIG. 3 is a front elevation of the switch device;

FIG. 4 is a plan view of FIG. 3; and

FIG. 5 is a section taken along line 5-5 of FIG. 4.

Like parts are indicated by corresponding reference characters throughout the several views of the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, a conventional furnace 1 is shown in FIG. 1. A cold air duct 3 and a hot air duct 5 are connected to the furnace in a conventional manner. An electronic air cleaner 7 is shown connected to the furnace between the latter and the cold air duct 3.

The electronic air cleaner includes filter cells (not shown) in which an electrostatic charge is maintained during electrical operation of the air cleaner. It is imperative that the electrostatic charge be supplied to the air filter only when air is being blown through the duct system since the maintenance of an electrostatic charge in the absence of air flow would create ozone and hence be dangerous.

In accordance with this invention, an automatic switching device 9 is provided which is adapted, in response to air flow past the device, to switch on the power unit of the electronic air cleaner. As soon as the air flow through the air cleaner stops, the device 9 will cause de-energization of the power unit. As shown in FIGS. 2-5, the ap paratus 9 includes an elongated support or bracket 11 adapted to be connected across the air cleaner. In particular, bracket 11, which may be formed by metal stamping operation, comprises an elongated grill or lattice portion 13 and an outer end portion 15, which may be curved as shown, or may be flat if desired. The other end portion of thevbracket 11 is L-shaped and includes a plate portion 17 adapted to be connected to the frame of the air cleaner. The bracket is adapted to be connected at its opposite ends to the cleaner 7 by conventional fastening means, such as screws, for example.

An electrical switch 19 is attached to plate 17 by bolts 21 and includes conventional electrical connecting terminals 23. Switch 19 is provided with a switch arm 25 which has an offset portion 27 adapted to extend through one end of a thin flexible sail strip or ribbon 29.

Sail strip 29 may be formed of a. very thin strip of Mylar, for example, and extends from switch arm 25 across grill 13 to end portion 15. As shown, the outer end of strip 29 extends around the curved end of portion 15 to the side thereof opposite the main portion of strip 29. The end of strip 29 is secured to the end portion 15 by a fastener, such as a small piece of tape 31, for example. It will be understood that the strip could be secured to portion 15 by other fasteners, such as a screw or bolt, for example.

The grill 13 is formed with a plurality of vertical ribs 33 and horizontal ribs 35 which are located in a plane. The grill also includes marginal fingers 37 which extend from opposite elongated sides of the grill. Elongated runners or flanges 39 connect the outer ends of the fingers 37 on opposite sides of the grill.

As shown, the end portion 15 of bracket 11 curves away from the plane a slight distance as shown in FIG. 4. The strip 29 which extends from the switch arm 25 to the outer end of portion 15 is spaced slightly away from the plane in which the vertical and horizontal ribs 33 and 35, respectively, are located.

It will be understood that the terminals 23 of switch 19 and connected to the power unit of the electronic air cleaner and the switch, when the switch arm 25 is in the solid line position shown in FIG. 3, is in a position or mode which prevents energization of the power unit.

Operation of the apparatus in this invention is as follows:

It will be assumed that the apparatus is attached to the electronic air cleaner in such a manner that the direction of air flow through the cleaner and the grill 13, when the furnace blower is operating, will be in the direction of the arrows A in FIG. 4. When the furnace blower is energized and begins moving air through the air cleaner 7, the strip 29 is blown from the generally straight line position shown in FIG. 4 to the curved broken line position shown therein. This movement of the strip causes the distance between the outer end of end portion 15 and the strip end connected to arm 25 to become shorter. Since the strip 29 is fixedly attached to end portion 15, the switch arm 25 is moved from a solid line switch de-actuating position shown in FIG. 3 to the dotted line switch actuating position shown therein, thereby actuating the switch 19 to the mode in which the power unit will be energized. The switch will remain in this mode due to the pull exerted by ship 29 as long as the air flowing through the electronic air cleaner is above a predetermined value. However, if the air flow should be diminished below the predetermined value or interrupted, the spring return force of the switch arm 25 will cause the latter to move from its broken line position in FIG. 3 to its solid line position therein, thereby interrupting the circuit through the power unit.

It will be noted that the switch apparatus of this invention causes de-energization of the electronic cleaner power unit whenever the air flow through the cleaner is interrupted. Thus, if the furnace blower motor should be energized, but for some reason, such as component failure, does not actuate the blower to force air through the duct system, the apparatus of this invention will prevent energization of the power unit.

It will be seen that only the weight of the thin strip 29 will be subjected to the forces of gravity regardless of the plane in which the device of this invention is installed. Since the strip 29 is very lightweight and is supported at its opposite ends, the gravitational forces are insuflicient to cause the latter to move the switch arm 25 to its broken line position in FIG. 3. It is only in response to the predetermined air flow that the strip 29 will be moved a suflicient amount to actuate the switch 19.

While the apparatus disclosed herein is shown in connection with an electronic air cleaner in a furnace duct system, it will be understood that it could be utilized in any air flow duct system wherein it is desired to complete a circuit through an electrical component only in response to the flow of air through the duct system.

In view of the foregoing, it will be seen that the several objects and other advantages of this invention are achieved.

Although only one embodiment of the invention has been disclosed and described, it is apparent that other embodiments and modifications of the invention are possible within the scope of the appended claims.

We claim:

1. Switching apparatus comprising a support, a switch mounted on said support and having a switch arm movable between a switch actuating position and a switch deactuating position, said support having an elongated portion extending away from said switch, an elongated sail strip connected at one end to said switch armand connected at the other end to said elongated portion at a point spaced from said switch arm, said sail strip in the absence of fluid flow thereagainst, being held in one predetermined position relative to said elongated portion by said switch arm and said support, said switch arm, in the absence of fluid flow against said sail strip, being in one of its said positions, said sail strip, in response to the flow of fluid thereagainst, moving from. said one predetermined position and moving said switch arm from said one position, said sail strip, when moved a predetermined amount from said one predetermined position, moving said switch arm to the other of its said positions.

2. Switching apparatus as set forth in claim 1 wherein said elongated portion of said support comprises a lattice member having a plurality of ribs extending throughout the length of said portion, and a plurality of ribs extending in a direction generally normal to the first mentioned ribs.

3. Switching apparatus as set forth in claim 1 wherein said sail strip comprises a thin, flexible strip.

4. Switching apparatus as set forth in claim 1 wherein said switch arm has an offset portion extending through said sail strip.

'5. Switching apparatus adapted to be connected to a support comprising a bracket, a switch mounted on said bracket and having a switch arm movable between a switch actuating position and a switch de-actuating position, said bracket having an elongated portion extending away from said switch and being adapted at its opposite ends for connection to said support, an elongated sail strip connected at one end to said switch arm and connected at the other end to said elongated portion at a point spaced from said switch arm, said sail strip, in the absence of fluid flow thereagainst, being held in one predetermined position relative to said elongated portion by said switch arm and said bracket, said switch arm, in the absence of fluid flow against said sail strip, being in one of its said positions, said sail strip in response to the flow of fluid thereagaint, moving from said one predetermined position and moving said switch arm from said one position, said sail strip, when moved a predetermined amount from said one predetermined position, moving said switch arm to the other of its said positions.

6. Switching apparatus as set forth in claim 5 wherein said elongated portion of said bracket comprises a lattice member having a plurality of ribs extending throughout the length of said portion, and a plurality of ribs extending in a direction generally normal to the first mentioned ribs.

7. Switching apparatus as set forth in claim 6 wherein said sail strip comprises a thin, flexible strip.

8. Switching apparatus as set forth in claim 7 wherein said switch arm has an offset portion extending through said sail strip.

(References on following page) 5 References Cited UNITED STATES PATENTS Havens ZOO-81.9 Greene ZOO-81.9 XR Hall 200--81.9 XR Reed ZOO-81.9 Long.

Breen 62187 Martin ZOO-81.9 XR

2/1964 Demuth et a1. 4/1965 Johnson.

U.S. Cl. X.R. 62-187; 98-40 

